This study is aimed at developing an animal model for atopic dermatitis, since no good animal model for this condition yet exists. It involvesisolating peripheral blood mononuclear cells (PBMC's) from atopic dermatitispatients. PBMC's (specifically CD4+ T cells) have been shown to be involved in the pathogenesis of this disorder. Once the PBMC's have been isolated from the atopic donors, they are engrafted into SCID mice. After the PBMC's have engrafted, antigens are introduced to the murine skin, in an attempt to trigger human CD4+ cell infiltration into the skin. Skin biopsies are then obtained for histological analysis, along with analysis for various cytokines (by RNA detection) to see if the atopic dermatitis phenotype has arisen.